MCQOPTIONS
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MCQOPTIONS
This section includes 1085 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
What will be the magnetic potential difference across the air gap of 2 cm length inmagnetic field of 200 AT/m ? |
| A. | 2 AT |
| B. | 4 AT |
| C. | 6 AT |
| D. | 10 AT |
| Answer» C. 6 AT | |
| 52. |
For which of the following parameter variation, the capacitance of the capacitorremains unaffected ? |
| A. | Distance between plates |
| B. | Area of the plates |
| C. | Nature of dielectric |
| D. | Thickness of the plates |
| Answer» E. | |
| 53. |
The force between two charges is 120 N. If the distance between the charges is doubled,the force will be |
| A. | 60 N |
| B. | 30 N |
| C. | 40 N |
| D. | 15 N |
| Answer» C. 40 N | |
| 54. |
For which of the following materials the saturation value is the highest ? |
| A. | Ferromagnetic materials |
| B. | Paramagnetic materials |
| C. | Diamagnetic materials |
| D. | Ferrites |
| Answer» E. | |
| 55. |
The law that the induced e.m.f. and current always oppose the cause producing them isdue to |
| A. | Faraday |
| B. | Lenz |
| C. | Newton |
| D. | Coulomb |
| Answer» C. Newton | |
| 56. |
The property of coil by which a counter e.m.f. is induced in it when the current throughthe coil changes is known as |
| A. | self-inductance |
| B. | mutual inductance |
| C. | series aiding inductance |
| D. | capacitance |
| Answer» B. mutual inductance | |
| 57. |
In an iron cored coil the iron core is removed so that the coil becomes an air cored coil.The inductance of the coil will |
| A. | increase |
| B. | decrease |
| C. | remain the same |
| D. | initially increase and then decrease |
| Answer» C. remain the same | |
| 58. |
Which of the following type of materials are not very important for engineeringapplications ? |
| A. | Ferromagnetic |
| B. | Paramagnetic |
| C. | Diamagnetic |
| D. | None of the above |
| Answer» D. None of the above | |
| 59. |
Hysteresis loop in case of magnetically hard materials is more in shape as compared tomagnetically soft materials. |
| A. | circular |
| B. | triangular |
| C. | rectangular |
| D. | none of the above |
| Answer» D. none of the above | |
| 60. |
If a copper disc is rotated rapidly below a freely suspended magnetic needle, themagnetic needle shall start rotating with a velocity |
| A. | less than that of disc but in opposite direction |
| B. | equal to that of disc and in the same direction |
| C. | equal to that of disc and in the opposite direction |
| D. | less than that of disc and in the same direction |
| Answer» E. | |
| 61. |
In a cable capacitor, voltage gradient ismaximum at the surface of the |
| A. | earth |
| B. | conduction |
| C. | sheath |
| D. | insulator |
| Answer» C. sheath | |
| 62. |
Which of the following is not a unit of inductance ? |
| A. | Henry |
| B. | Coulomb/volt ampere |
| C. | Volt second per ampere |
| D. | All of the above |
| Answer» C. Volt second per ampere | |
| 63. |
An average voltage of 10 V is induced in a 250 turns solenoid as a result of a change influx which occurs in 0.5 second. The total flux change is |
| A. | 20 Wb |
| B. | 2 Wb |
| C. | 0.2 Wb |
| D. | 0.02 Wb |
| Answer» E. | |
| 64. |
Two coils have self-inductances of 10 H and 2 H, the mutual inductance being zero. Ifthe two coils are connected in series, the total inductance will be |
| A. | 6 H |
| B. | 8 H |
| C. | 12 H |
| D. | 24 H |
| Answer» D. 24 H | |
| 65. |
The electric field intensity at a point situated 4 metres from a point charge is 200 N/C. Ifthe distance is reduced to 2 metres, the field intensity will be |
| A. | 400 N/C |
| B. | 600 N/C |
| C. | 800 N/C |
| D. | 1200 N/C |
| Answer» D. 1200 N/C | |
| 66. |
A coil with negligible resistance has 50V across it with 10 mA. The inductive reactanceis |
| A. | 50 ohms |
| B. | 500 ohms |
| C. | 1000 ohms |
| D. | 5000 ohms |
| Answer» E. | |
| 67. |
When two ends of a circular uniform wire are joined to the terminals of a battery, thefield at the centre of the circle |
| A. | will be zero |
| B. | will be infinite |
| C. | will depend on the amount of e.m.f. applied |
| D. | will depend on the radius of the circle |
| Answer» E. | |
| 68. |
The electrostatic force between two charges of one coulomb each and placed at adistance of 0.5 m will be |
| A. | 36 x 10fa |
| B. | 36 x 107 N |
| C. | 36 x 108 N |
| D. | 36 x 109 N |
| Answer» E. | |
| 69. |
If the area of hysteresis loop of a material is large, the hysteresis loss in this materialwill be |
| A. | zero |
| B. | small |
| C. | large |
| D. | none of the above |
| Answer» D. none of the above | |
| 70. |
When a conductor moves in the field, so that it makes an angle 8 with the lines of flux,the force F is given as : F = Bl sin2 0. |
| A. | Yes |
| B. | No |
| C. | none |
| D. | none |
| Answer» C. none | |
| 71. |
Which of the following is a ferromagnetic material ? |
| A. | Tungsten |
| B. | Aluminium |
| C. | Copper |
| D. | Nickel |
| Answer» E. | |
| 72. |
The magneto-motive force is |
| A. | the voltage across the two ends of exciting coil |
| B. | the flow of an electric current |
| C. | the sum of all currents embraced by one line of magnetic field |
| D. | the passage of magnetic field through an exciting coil |
| Answer» D. the passage of magnetic field through an exciting coil | |
| 73. |
The number of Faraday tubes of flux passing through a surface in an electric field iscalled |
| A. | electric flux |
| B. | electric flux density |
| C. | magnetic flux density |
| D. | electric charge density |
| Answer» B. electric flux density | |
| 74. |
"The surface integral of the normal component of the electric displacement D over anyclosed surface equals the charge enclosed by the surface". The above statement is associated with |
| A. | Gauss's law |
| B. | Kirchhoff s law |
| C. | Faraday's law |
| D. | Lenz's law |
| Answer» B. Kirchhoff s law | |
| 75. |
A 200 turn coil has an inductance of 12 mH. If the number of turns is increased to 400turns, all other quantities (area, length etc.) remaining the same, the inductance will be |
| A. | 6 mH |
| B. | 14 mH |
| C. | 24 mH |
| D. | 48 mH |
| Answer» E. | |
| 76. |
________field is associated with the capacitor. |
| A. | Electric |
| B. | Magnetic |
| C. | Both (a) and (b) |
| D. | None of the above |
| Answer» B. Magnetic | |
| 77. |
Energy stored in the electric field of a capacitor C when charged from a D.C source ofvoltage V is equal to joules |
| A. | CV2 |
| B. | C2V |
| C. | CV2 |
| D. | CV |
| Answer» B. C2V | |
| 78. |
Voltage applied across a ceramic dielectric produces an electrolytic field 100 timesgreater than air. What will be the value of dielectric constant ? |
| A. | 50 |
| B. | 100 |
| C. | 150 |
| D. | 200 |
| Answer» C. 150 | |
| 79. |
A positive and a negative charge are initially 50 mm apart. When they are moved closetogether so that they are now only 10 mm apart, the force between them will be |
| A. | 5 times smaller than before |
| B. | 5 times greater than before |
| C. | 10 times greater than before |
| D. | 25 times larger than before |
| Answer» E. | |
| 80. |
Which of the following is the unit of magnetic flux density ? |
| A. | weber |
| B. | lumens |
| C. | tesla |
| D. | none of the above |
| Answer» D. none of the above | |
| 81. |
Which of the following materials are dia-magnetic ? |
| A. | Silver |
| B. | Copper |
| C. | Silver and copper |
| D. | Iron |
| Answer» D. Iron | |
| 82. |
Out of the following capacitors of identical rating which one will have the smallestdimensions ? |
| A. | Aluminium foil capacitor |
| B. | Mica capacitor |
| C. | Ceramic capacitor |
| D. | Paper capacitor |
| Answer» D. Paper capacitor | |
| 83. |
A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. Thestrength of electric field is |
| A. | 100 kV/m |
| B. | 10 kV/m |
| C. | 5 kV/m |
| D. | 2 kV/m |
| Answer» B. 10 kV/m | |
| 84. |
While testing a capacitor with ohm-metre, if the capacitor shows charging, but the finalresistance reading is appreciably less than normal, it can be concluded that the capacitor is |
| A. | short-circuited |
| B. | open circuited |
| C. | alright |
| D. | leaky |
| Answer» E. | |
| 85. |
What will happen to an insulating medium if voltage more than the breakdownvoltage is applied on it ? |
| A. | It will become magnetic |
| B. | It will melt |
| C. | It will get punctured or cracked |
| D. | Its molecular structure will get changed |
| Answer» D. Its molecular structure will get changed | |
| 86. |
Permeability in a magnetic circuit corresponds to______ in an electric circuit. |
| A. | resistance |
| B. | resistivity |
| C. | conductivity |
| D. | conductance |
| Answer» D. conductance | |
| 87. |
The polarity of the induced voltage can be determined by using the left-hand generatorrule. |
| A. | Yes |
| B. | No |
| C. | none |
| D. | none |
| Answer» B. No | |
| 88. |
The capacitance C is charged through a resistance R. The time constant of the chargingcircuit is given by |
| A. | CIR |
| B. | 1/RC |
| C. | RC |
| D. | RIC |
| Answer» D. RIC | |
| 89. |
Which circuit element(s) will oppose the change in circuit current ? |
| A. | Resistance only |
| B. | Inductance only |
| C. | Capacitance only |
| D. | Inductance and capacitance |
| Answer» C. Capacitance only | |
| 90. |
Point out the wrong statement.Magnetic leakage is undesirable in electric machines because it |
| A. | lowers their power efficiency |
| B. | increases their cost of manufacture |
| C. | leads to their increased weight |
| D. | produces fringing |
| Answer» B. increases their cost of manufacture | |
| 91. |
The self-inductance of the coil may be defined as equal to the e.m.f. induced in voltswhen the current in the circuit changes at the rate of unit weber turns. |
| A. | Yes |
| B. | No |
| C. | none |
| D. | none |
| Answer» C. none | |
| 92. |
Find the force acting on a conductor 3m long carrying a current of 50 amperes at rightangles to a magnetic field having a flux density of 0.67 tesla. |
| A. | 100 N |
| B. | 400 N |
| C. | 600 N |
| D. | 1000 N |
| Answer» B. 400 N | |
| 93. |
Two plates of a parallel plate capacitor after being charged from a constant voltagesource are separated apart by means of insulated handles, then the |
| A. | Voltage across the plates increases |
| B. | voltage across the plates decreases |
| C. | charge on the capacitor decreases |
| D. | charge on the capacitor increases |
| Answer» C. charge on the capacitor decreases | |
| 94. |
An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of currentmust be |
| A. | 64 A/s |
| B. | 32 A/s |
| C. | 16 A/s |
| D. | 4 A/s |
| Answer» E. | |
| 95. |
Out of the following statements, concerning an electric field, which statement is not true ? |
| A. | The electric intensity is a vector quantity |
| B. | The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point |
| C. | An electric field is defined as a point in space at which an electric charge would experienc* a force |
| D. | Unit field intensity in the exertion of a force of one newton on a charge of one coulomb |
| Answer» C. An electric field is defined as a point in space at which an electric charge would experienc* a force | |
| 96. |
A single core cable used on 33000 V has conductor diameter 10 mm and the in¬ternaldiameter of sheath 25 mm. The maximum electrostatic stress in the cable is |
| A. | 62 x 105 V/m |
| B. | 72 x 105 V/m |
| C. | 82 x 105 V/m |
| D. | 92 x 105 V/m |
| Answer» C. 82 x 105 V/m | |
| 97. |
A rectangular magnet of magnetic moment M is cut into two piece of same length, themagnetic moment of each piece will be |
| A. | M |
| B. | M/2 |
| C. | 2 M |
| D. | M/4 |
| Answer» C. 2 M | |
| 98. |
Acharge which when placed in vacuum from an equal and similar charge repels with aforce of 9 x 10 N, is known as |
| A. | milli-coulomb |
| B. | micro-coulomb |
| C. | pico-coulomb |
| D. | coulomb |
| Answer» C. pico-coulomb | |
| 99. |
While comparing magnetic and electric circuits, the flux of magnetic circuit is comparedwith which parameter of electrical circuit ? |
| A. | E.m.f. |
| B. | Current |
| C. | Current density |
| D. | Conductivity |
| Answer» C. Current density | |
| 100. |
Which of the following circuit element stores energy in the electromagnetic field ? |
| A. | Inductance |
| B. | Condenser |
| C. | Variable resistor |
| D. | Resistance |
| Answer» B. Condenser | |